I understand why you'd add courtesy accidentals, but I was browsing through some old sheet music lying around here and came across this, and can't seem to come up with a reason for this natural in bar 2:
What am i missing here? The signature's G and only the F's should be raised, so why naturalise the G's? I don't have any training, so maybe this is simply something I've missed in my self-study.
(It's from "Alec Eiffel" by Pixies BTW)